1. Technical Field
The invention relates generally to an improved tool. More particularly, the invention relates to an improved tool and method for the adjustment of wheel camber. Specifically, the invention relates to a tool which pneumatically moves a vehicle wheel in a precise fashion so that its camber can be adjusted by a single person.
2. Background Information
The term "camber" refers to the angle between a vehicle wheel and the vertical axis. Proper adjustment of the camber angle is essential to maintain vehicle stability and performance, and assures proper tread wear and tread life.
Motor vehicles require periodic adjustment of their wheel camber, due to a number of factors including tire wear and replacement, strut wear and replacement, and road hazards, among others. With the generally increasing durability of automobiles, a given vehicle will require numerous camber adjustment over the course of its usable lifetime.
On many vehicles, proper camber is maintained by a number of bolts which extend through two flanges, one of which is attached to the overhead strut, and the other of which is connected to the spindle upon which the wheel is mounted. When these bolts are tightened, a compression load is created between the two flanges, causing the flanges to be frictionally held together, maintaining the proper orientation between the strut and the wheel, which in turn maintains the wheel camber.
To adjust the wheel camber, the vehicle must first be positioned such that the wheels fully support the weight of the vehicle without the use of jacks or lifts to reduce the weight borne by the wheels. The bolts must then be loosened and the wheel moved in relation to the overhead strut until the correct camber setting is achieved. Another specially-designed tool known in the art moved the wheel by means of a specially designed screw-driven tool which caused two members to expand in the space between the wheel and the overhead strut, applying a load inwardly against the strut and outwardly against the wheel, with the result that the wheel would move in relation to the fixed strut. The screw drive on the specially-designed tool would be adjusted until the correct camber setting was achieved, and the bolts would then be tightened to maintain the correct camber setting.
Since the adjustment of camber must occur while the vehicle weight is supported by the wheels, movement of the wheel requires that a significant amount of force be applied by the specially-designed tool to both the strut and the wheel. Since the specially-designed tool must fit through the small space between the top of the vehicle tire and the lower edge of the vehicle fender, the tool must necessarily be of a very low profile. Since the specially-designed tool must apply a significant force to the strut, yet be designed with low profile, the force is applied by the tool to a very small area of surface on the strut, causing a high level of bearing stress at the point of force application. This bearing stress may result in plastic deformation or damage to the strut.
Moreover, since an angle exists between the strut and the plane of the wheel, and the load is applied inside this angle by the specially-designed tool to the strut and the wheel, the resultant force applied to the strut must include both a compressive component normal to the strut surface and a frictional component parallel to the surface. Depending upon the relative magnitudes of these compressive and frictional forces, which in turn depends upon the angle between the strut and the plane of the wheel, the tool may be caused to slip from the strut if the angle becomes too great or if the tool is misapplied or accidentally bumped by the mechanic. Such a slip can result both in damage to the vehicle and injury to the user or others nearby.
Additionally, since the screw adjustment means of the specially-designed tool is a fixed component of the tool, any adjustment of the screw drive must be performed at the location where the tool is applied to the wheel, which will typically be immediately outside the wheel opening of the vehicle fender. Since computers are often used in the modern automotive workshops of today, a mechanic utilizing such a computer in concert with the specially-designed tool will typically be required to walk back and forth between the tool and the computer.
Alternatively, wheel camber can be adjusted without the use of the specially-designed tool by utilizing shop personnel to adjust wheel camber. More particularly, the bolts are loosened, and the wheel is manually moved to the correct camber position while a second person operates the computer and tightens the bolts as the wheel is held in position. While this system is functional, it is difficult to do accurately, and requires the use of two people, rather than one, significantly increasing the cost of adjusting wheel camber.
Therefore, the need exists for low cost, portable mechanism which allows the user to quickly adjust and hold the position of a vehicle tire for adjustment of its camber, while reducing the time wasted by the user in walking between the means of adjustment and a computer, and while reducing the risk of damage to the vehicle components and injury to the user.